Saw blade

ABSTRACT

A saw blade in which a structure pattern comprising first teeth group A and a second teeth group B each having a plurality of set teeth is repeated, wherein the saw blade has at least one or both of the following conditions, i.e., a condition in which a tooth height of the second teeth group B is lower than that of the first teeth group A, and a condition in which a set amount of the second teeth group B is smaller than that of the first teeth group A, and wherein the first teeth group A has at least one spur tooth.

TECHNICAL FIELD

[0001] The present invention relates to a saw blade such as a band saw,a hacksaw, a circular saw and the like as a tool for cutting a materialto be cut (workpiece) in cutting operation.

BACKGROUND TECHNIQUE

[0002] A band mill is conventionally used as an apparatus for cutting alarge metal workpiece. In a band saw blade used for the band mill, inorder to cope with chatter vibration or noise, a pattern of set teeth isset to various set patterns such as raker set, wave set and straightset, and pitch between the teeth is made non-uniform. In order to copewith difficult-to-machine material such as stainless steel, there isdeveloped a saw blade in which a plurality of teeth of the saw blade arevaried in height or the set amount of the plurality of set teeth isvaried.

[0003] To meet commercial requirements, there have been developedvarious saw blades such as a saw blade in which angles of tips of sawteeth are variously changed, a back surface of the saw blade iscorrugate, or a curve line connecting tips of the teeth of the saw bladeis corrugated.

[0004] Concerning also a band mill which cuts a metal workpiece forexample, various bandmills have been developed in accordance with usageof cutting operations. For example, cutting methods of the band millsare roughly divided, there are two kinds of methods, i.e., (1) a case inwhich a cutting speed is constant irrespective of a cutting length of aworkpiece, and (2) a case in which the cutting speed is variable inaccordance with the cutting length of a workpiece.

[0005] The methods (2) in which the cutting speed is variable inaccordance with the cutting length of a workpiece can further be dividedinto

[0006] (2-1) a method for controlling back pressure generated in acylinder using a hydraulic cylinder,

[0007] (2-2) a method for controlling a flow rate in accordance withcutting resistance using hydraulic cylinder,

[0008] (2-3) a CNC controlling method in which a shape of a workpiece ispreviously input, the cutting length of a workpiece is calculated eachtime and the cutting speed is changed,

[0009] (2-4) a CNC controlling method in which a cutting resistance isdetected, and the cutting speed is changed in accordance with thecutting resistance,

[0010] (2-5) a weight of a housing to which the sawblade is mounted ismechanically adjusted and restrained, and a workpiece is cut by freefall.

[0011] Conventionally, band mill such as a small and inexpensiveportable band saws are widely used. Generally, the small portable bandsaw, a lateral type band saw are of hinge type in which a saw bladehousing is vertically swung such as to draw an arc, and the method of(2-5) is frequently used. Such a band mill is called “light-load sawmill” herein after in this specification.

[0012] The light-load saw mills in the common market are suitable forcutting a relatively small workpiece in a cutting operation on abuilding site of steel construction. Although such workpiece shapes arelimited to small objects, the kinds of the workpiece shapes vary widely,and cutting operations of workpieces such as different shaped steels,pipes and small-diameter solid materials are carried out.

[0013] In the light-load saw mills as described above, as shown in FIGS.1A and 1B, one set pattern comprises three teeth, i.e., one spur tooth Sand a pair of left and right set tooth L and R having constant setamount in the lateral direction, and this set pattern is repeated. Whena solid material W having a diameter of 50 mm is cut using a saw blade101 having a pitch of 4 mm as shown in FIG. 3, an appropriate cuttingoperation can be carried out. When a pipe material W having a diameterof 50 mm and a thickness of 3 mm is cut using the same saw blade 101 asshown in FIG. 4, however, there is a problem that the saw blade 101 isprone to be broken off.

[0014] This is because that although the pitch of the saw blade 101 is 4mm, the thickness of the pipe material W is 3 mm and the cutting speedof the saw blade 101 is close to a free fall of a housing load G andthus, if the cutting operation by the saw blade 101 reaches near thecenter of the pipe material W in this cutting condition, the workpiece Wenters between a tip and a tip of the saw blade 101, and abrupt freefall is generated, a cutting amount becomes excessively increased andthus, the teeth are prone to be broken.

[0015] As a current method for solving this problem, as shown in FIGS.2A and 2B, it is common to cut a pipe material W using a saw blade 103having a pitch smaller than a thickness of the pipe material W. FIG. 5shows a state in which a pipe material W having a thickness of 3 mm anda diameter of 50 mm is cut using a saw blade 103 (saw blade shown inFIGS. 2A and 2B) having a pitch of 2 mm.

[0016] Under this condition, since the pitch of the saw blade 103 is assmall as 2 mm with respect to the 3 mm thickness of the pipe material W,even if the saw blade 103 reaches near the center of the pipe material,the workpiece W does not enter between a tip and a tip of the saw blade103, and abrupt free fall is not generated, an appropriate cuttingoperation is carried out.

[0017] If a solid material W (workpiece shown in FIG. 3) having adiameter of 50 mm is cut using the same saw blade 103, i.e., the sawblade 103 (saw blade shown in FIGS. 2A and 2B) having the pitch of 2 mm,however, since the pitch of the saw blade 103 is sufficiently smallerthan the diameter of the workpiece W, abrupt free fall is not generatedand the excessive cutting is not generated. However, the number of teethof the saw blade 103 acting on a cutting length of the workpiece W islarge, and a cutting amount of each tooth with respect to the workpieceW becomes small. Therefore, there is a problem that the cutting timebecomes long as compared with a case in which a solid material W is cutby the saw blade 101 having the pitch of 4 mm.

[0018] For the above-described reason, when a workpiece such as a solidmaterial and a pipe material is cut, there is a problem that it isnecessary to exchange saw blade having an appropriate pitch inaccordance with shape and size of the workpiece W and it takes time andlabor for exchanging the saw blades.

[0019] Therefore, various workpieces are cut on building site and thelike, and labor for exchanging saw blades having different pitches inaccordance with shape and size of workpieces is not negligible. Even ifa saw blade having relatively small pitch is previously mounted for thesake of preventing the teeth from being broken, if a workpiece havingrelatively long cutting length, a problem in which the cutting timebecomes long is not negligible.

[0020] The present invention has been accomplished to solve the aboveproblems, and it is an object of the invention to provide a saw bladecapable of efficiently cutting workpieces having relatively long orsmall cutting length while preventing the teeth from being broken.

DISCLOSURE OF THE INVENTION

[0021] To achieve the above object, a first aspect of the inventionprovides a saw blade in which a set pattern comprising a combination ofa first teeth group having a spur tooth and left and right laterallybent set teeth and a second teeth group having left and right laterallybent saw teeth is appropriately repeated, wherein set amounts of theleft and right saw teeth of the second teeth group are smaller than orequal to set amounts of the left and right saw teeth of the first teethgroup.

[0022] A second aspect of the invention provides a saw blade in which aset pattern comprising a combination of a first teeth group having aspur tooth and left and right laterally bent set teeth and a secondteeth group having left and right laterally bent saw teeth isappropriately repeated, wherein a tooth height of the second teeth groupis lower than a tooth height of the first teeth group.

[0023] According to a third aspect of the invention, in the saw blade ofthe second aspect, set amounts of the left and right saw teeth of thesecond teeth group are smaller than or equal to set amounts of the leftand right saw teeth of the first teeth group.

[0024] A fourth aspect of the invention provides a saw blade in which aset pattern comprising a combination of first and second teeth groupeach having at least a spur tooth and a pair of left and right laterallybent set teeth is appropriately repeated, wherein a tooth height of thesaw tooth of the second teeth group is lower than a tooth height of thesaw tooth of the first teeth group, a tip pitch including a garret ofthe saw tooth of the second teeth group is smaller than a tip pitchincluding a garret of the saw tooth of the first teeth group, setamounts of the left and right set teeth of the second teeth group areequal to or smaller than set amounts the left and right set teeth of thefirst teeth group.

[0025] A fifth aspect of the invention provides a saw blade in which aset pattern comprising a combination of a first teeth group having atleast a spur tooth and a pair of left and right laterally bent set teethand a second teeth group having at least a pair of left and right setteeth is appropriately repeated, wherein a tooth height of the saw toothof the second teeth group is lower than a tooth height of the saw toothof the first teeth group, a tip pitch including a garret of the sawtooth of the second teeth group is smaller than a tip pitch including agarret of the saw tooth of the first teeth group, set amounts of theleft and right set teeth of the second teeth group are equal to orsmaller than set amounts the left and right set teeth of the first teethgroup.

[0026] A saw blade according to a sixth aspect, in the saw blade of anyone of the first to fifth aspects, the second teeth group includes aspur tooth, the number of teeth of the first teeth group and the numberof teeth of the second teeth group are the same.

[0027] A saw blade according to a seventh aspect, in the saw blade ofany one of the first to sixth aspects, the number of the left and rightsaw teeth of the first teeth group and the number of left and right sawteeth of the second teeth group are the same.

[0028] A saw blade according to an eighth aspect, in the saw blade ofany one of the first to seventh aspects, the first teeth groups and thesecond teeth groups are alternately arranged.

[0029] A saw blade according to a ninth aspect, in the saw blade of anyone of the first to eighth aspects, the number of teeth of the secondteeth group is greater than the number of teeth of the first teethgroup.

[0030] A saw blade according to a tenth aspect, in the saw blade of anyone of the first to ninth aspects, the number of teeth of the firstteeth group is greater than the number of teeth of the second teethgroup.

[0031] A saw blade according to an eleventh aspect, in the saw blade ofany one of the first to tenth aspects, saw teeth of the left and rightsaw teeth of the first and second teeth group which are bent in the samedirection are continuously arranged.

[0032] A saw blade according to a twelfth aspect, in the saw blade ofany one of the first to tenth aspects, saw teeth of the left and rightsaw teeth of the first and second teeth group which are bent in the samedirection are not continuously arranged.

[0033] A saw blade according to a thirteenth aspect, in the saw blade ofany one of the first to twelfth aspects, pitches between the teeth arenot equal to each other.

[0034] A saw blade according to a fourteenth aspect, in the saw blade ofany one of the first to thirteenth aspects, the non equal pitches aretwo kinds of pitches.

[0035] A saw blade according to a fifteenth aspect, in the saw blade ofany one of the first to fourteenth aspects, a height difference betweenthe teeth of the first teeth group and the teeth of the second teethgroup is 0.2 mm or less.

[0036] A saw blade according to a sixteenth aspect, in the saw blade ofany one of the first to fifteenth aspects, a bottom of a garret of thesaw tooth of the second teeth group is located closer to a tip than agarret of the saw tooth of the first teeth group.

[0037] A saw blade according to a seventeenth aspect, in the saw bladeof the fourth or fifth aspect, the saw tooth of the second teeth groupis disposed between saw teeth of the first teeth group.

[0038] As described above, according to the saw blade of the presentinvention, the set pattern comprises a combination of the first teethgroup having the spur tooth and left and right set teeth having hightooth height, and the second teeth group having the left and right setteeth having set amount smaller than set amount of the set teeth of thefirst teeth group.

[0039] Therefore, it is possible to easily cut a solid material and apipe material, and to carry out the cutting operation without breakingthe teeth, and the above-described conventional problem can be solved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040]FIG. 1A is a front view showing a portion of tip shape of aconventional saw blade.

[0041]FIG. 1B is a bottom view showing a portion of the tip shape of theconventional saw blade shown in FIG. 1A.

[0042]FIG. 2A is a front view showing a portion of tip shape of aconventional saw blade.

[0043]FIG. 2B is a bottom view showing a portion of the tip shape of theconventional saw blade shown in FIG. 2A.

[0044]FIG. 3 is an explanatory view of a state in which a solid materialis cut by a saw blade having a pitch of 4 mm.

[0045]FIG. 4 is an explanatory view of a state in which a pipe materialhaving a thickness of 3 mm is cut by a saw blade having a pitch of 4 mm.

[0046]FIG. 5 is an explanatory view of a state in which a pipe materialhaving a thickness of 3 mm is cut by a saw blade having a pitch of 2 mm.

[0047]FIG. 6A is a front view showing a portion of tip shape of a sawblade according to a first embodiment of the present invention.

[0048]FIG. 6B is a bottom view showing a portion of the tip shape of theconventional saw blade shown in FIG. 6A.

[0049]FIG. 6C is a bottom view showing a modification of the tip shapeof the saw blade shown in FIG. 6B.

[0050]FIG. 7A is a front view showing a portion of tip shape of a sawblade according to a second embodiment of the present invention.

[0051]FIG. 7B is a bottom view showing a portion of the tip shape of theconventional saw blade shown in FIG. 7A.

[0052]FIG. 7C is a bottom view showing a modification of the tip shapeof the saw blade shown in FIG. 7B.

[0053]FIG. 8A is a front view showing a portion of tip shape of a sawblade according to a third embodiment of the present invention.

[0054]FIG. 8B is a bottom view showing a portion of the tip shape of theconventional saw blade shown in FIG. 8A.

[0055]FIG. 9A is a front view showing a portion of tip shape of a sawblade according to a fourth embodiment of the present invention.

[0056]FIG. 9B is a bottom view showing a portion of the tip shape of theconventional saw blade shown in FIG. 9A.

[0057]FIG. 10A is a front view showing a portion of tip shape of a sawblade according to a fifth embodiment of the present invention.

[0058]FIG. 10B is a bottom view showing a portion of the tip shape ofthe conventional saw blade shown in FIG. 10A.

[0059]FIG. 11A is a front view showing a portion of tip shape of a sawblade according to a sixth embodiment of the present invention.

[0060]FIG. 11B is a bottom view showing a portion of the tip shape ofthe conventional saw blade shown in FIG. 11A.

[0061]FIG. 12A is a front view showing a portion of tip shape of a sawblade according to a seventh embodiment of the present invention.

[0062]FIG. 12B is a bottom view showing a portion of the tip shape ofthe conventional saw blade shown in FIG. 12A.

[0063]FIG. 13A is a front view showing a portion of tip shape of a sawblade according to an eighth embodiment of the present invention.

[0064]FIG. 13B is a bottom view showing a portion of the tip shape ofthe conventional saw blade shown in FIG. 13A.

[0065]FIG. 14A is a front view showing a portion of tip shape of a sawblade according to a ninth embodiment of the present invention.

[0066]FIG. 14B is a bottom view showing a portion of the tip shape ofthe conventional saw blade shown in FIG. 14A.

[0067]FIG. 14C is a bottom view showing a modification of the tip shapeof the saw blade shown in FIG. 14B.

[0068]FIG. 15A is a front view showing a portion of tip shape of a sawblade according to a tenth embodiment of the present invention.

[0069]FIG. 15B is a bottom view showing a portion of the tip shape ofthe conventional saw blade shown in FIG. 15A.

[0070]FIG. 15C is a bottom view showing a modification of the tip shapeof the saw blade shown in FIG. 15B.

BEST MODE FOR CARRYING OUT THE INVENTION

[0071] Embodiments of the present invention will be explained using thedrawings. Saw blade according to the embodiments cut workpieces bymoving the saw blade in a right direction in the drawings.

[0072] Referring to FIGS. 6A and 6B, in a saw blade 1 according to afirst embodiment of the present invention, a set pattern of acombination of a first teeth group (saw teeth belonging to the firstteeth group are shown with symbols A) and a second teeth group (sawteeth belonging to the second teeth group are shown with symbols B) isrepeated appropriately. The first teeth group has a spur tooth S whichis not bent in the lateral direction (thickness direction of the sawblade 1) with respect to the saw blade 1 and a pair of left and rightset teeth Lw and Rw having relatively large set amount in the lateraldirection (i. e., set width is wide). The second teeth group has a pairof left and right set teeth Ln and Rn having set amount (i.e., set widthis narrow) smaller than the set amount of the left and right set teethLw and Rw of the first teeth group A.

[0073] The saw blade 1 run from left to right in the drawings to cut aworkpiece W. In this case, in the cutting operation, the teeth Lw, Ln,Rw, Rn, S and S abut against the workpiece W in this order to proceedthe cutting operation.

[0074] In the saw blade 1 shown in FIGS. 6A and 6B, the first teethgroup A comprises four teeth, i.e., the two spur teeth S, and the pairof left and right set teeth Lw and Rw having relatively large setamount. The second teeth group B comprises two teeth, i.e., the pair ofleft and right set teeth Ln and Rn having set amount smaller than theset amount of the left and right set teeth Lw and Rw of the first teethgroup A. The first teeth group A and the second teeth group B arecombined to form the set pattern. Tip pitches P1 are the same and areset to 2 mm for example.

[0075] When a workpiece W such as a solid material shown in FIG. 3having relatively long cutting length is cut using the saw blade 1having the above structure, since the set amounts of the left and rightset teeth Ln and Rn of the second teeth group B are smaller than thoseof the left and right set teeth Lw and Rw of the first teeth group A, aforce contributing to the cutting operation when the workpiece W is cutsuch as to widen the cutting groove is small. Since the force is small,the pitch of the saw blade becomes great correspondingly. That is, ifthe second teeth group B having a smaller force contributing to thecutting operation is ignored, a distance of the set teeth which largelycontributes to the cutting operation is a distance between the left settooth Lw and the right set tooth Rw, and between the right set tooth Rwand the spur tooth S of the first teeth group A which mainly carries outthe cutting operation. It looks as if a saw blade having large pitch(P1×2) cuts the workpiece W. A distance between the spur teeth S and Sis the original pitch P1.

[0076] Therefore, solid materials shown in FIG. 3 were cut using the sawblade 1 of the present embodiment and the conventional saw blade 103shown in FIGS. 2A and 2B under the same cutting conditions such asrunning speeds of band mill and saw blade and cutting loads, and resultswere compared, and cutting time of the saw blade 1 of the presentembodiment was shorter.

[0077] At the time of the above cutting operation, the saw blade 1 cutthe workpiece W with saw tooth pitch of (P1×2) pitch and the pitch P1,resonance of the saw blade at the time of cutting operation isrestrained and noise is restrained. Since the left and right set toothare equal to each other, component of force in the lateral directionacting on the saw blade is canceled.

[0078] The cutting time is compared including the conventional saw blade101 shown in FIGS. 1A and 1B, a result is saw blade 101<saw blade 1<sawblade 103, and when a solid material is cut, cutting time is shorterthan the conventional saw blade 103 shown in FIGS. 2A and 2B.

[0079] If a workpiece W such as a pipe material shown in FIG. 5 is cutusing a saw blade 1 shown in FIGS. 6A and 6B, the pitch P1 of the sawblade is as small as 2 mm with respect to 3 mm thickness of the pipematerial, and even if the saw blade 1 reaches near the center of thepipe material, the workpiece W does not enter between the tips of thesaw blade, and abrupt free fall is not generated, and the workpiece W isappropriately cut without breaking the teeth.

[0080] That is, at the time of cutting of a workpiece, when a cuttingresistance is large and a cutting speed relatively tends to be smalllike a case in which a solid material is cut, saw teeth of the firstteeth group A mainly cut. When the cutting resistance is relativelysmall and the cutting speed tends to be relatively large like a case inwhich a pipe material is cut, both the first teeth group and the secondteeth group cut together, and it is possible to efficiently cut aworkpiece having relatively long cutting length and a workpiece havingsmall cutting length without breaking the teeth. As a result, labor forexchanging the saw blades in accordance with workpieces can be omitted,and a consumption amount of a saw blade can also be reduced.

[0081] As shown in FIG. 6C, it is possible that the set amounts of theleft and right set teeth Lw and Rw of the first teeth group A and theset amounts of the set teeth Ln and Rn of the second teeth group B aresubstantially the same. In this case, the above-described effect can beexhibited, and since the set teeth Ln and Rn of the second teeth group Bslightly contribute to the cutting operation, a cut section of a workpiece W is shaven, and precision of the cut section is further enhanced.

[0082]FIGS. 7A and 7B show a saw blade 3 of a second embodiment of theinvention. In the saw blade 3, there is a height difference H1 betweensaw teeth corresponding to the first teeth group A and saw teethcorresponding to the second teeth group B, and distances between the sawteeth are equal pitches P1.

[0083] In other words, the tips of the spur teeth S, Lw and Rw arearranged such as to coincide with a first phantom line F1 shown withchain line. On the other hand, the tips of the saw teeth St, Ln and Rnare arranged such as to coincide with a second phantom line F2 shownwith chain line. A height difference between the first phantom line F1and the second phantom line F2 corresponds to the height difference H1of the tooth height of the saw teeth.

[0084] Since there is the height difference H1 between the tips of theset teeth S, Lw and Rw and the tips of the saw teeth St, Ln and Rn,depths of garrets thereof are different. That is, the set teeth Ln andRn belonging to the second teeth group B have low tooth heights (asshown with (L)), and the front garret (on the right side in the drawingsand upstream of the moving direction of the saw blade) is shallower thanthe garret in front of the saw teeth St, Lw, Rw belonging to the firstteeth group A. By making the tooth height lower and the front garretshallower in this manner, the rigidity of the saw tooth belonging to thesecond teeth group B is enhanced, and bending of the saw tooth in theset bending direction by the cutting resistance when a workpiece is cutby the saw tooth can be restrained, and the cutting ability can beenhanced.

[0085] Concerning the height difference between the left and right sawteeth of the first teeth group A and the left and right saw teeth of thesecond teeth group B, the tooth height of the set tooth having small setamount of the second teeth group B is the lowest. In other words, a settooth having low tooth height has a set amount smaller than that of aset tooth having high tooth height.

[0086] More specifically, the first teeth group A comprises total threeteeth, i.e., the one spur tooth S having high tooth height (as shownwith (H)), and the pair of left and right set teeth Lw and Rw havingrelatively large set amounts and having high tooth height (as shown with(H)). The second teeth group B comprises total three teeth, i.e., theone set tooth Set tooth having a smaller tooth height than that of thespur tooth S of the first teeth group A, and the pair of set teeth Lnand Rn having smaller tooth height and smaller set amounts than those ofthe left and right set teeth Lw and Rw of the first teeth group A. Thenumber of the set teeth and the left and right saw teeth are the same,and one set pattern is constituted by total six saw teeth of the firstteeth group A and the second teeth group B. The saw teeth of the firstteeth group A and the saw teeth of the second teeth group B are disposedalternately.

[0087] In the saw blade 3, the height difference H1 between the tips ofthe saw teeth of the first teeth group A and the saw teeth of the secondteeth group B are set to such a degree that when the cutting length islong and cutting resistance in the cutting direction is large and thecutting speed is relatively slow like a case when a solid material shownin FIG. 3 is cut, the cutting operation is mainly carried out by the sawteeth of the first teeth group A, and when the cutting resistance in thecutting direction is small and the cutting speed is prone to berelatively high like a case when a pipe material shown in FIG. 5 is cut,the cutting operation is carried out by both the first teeth group A andsecond teeth group B.

[0088] According to various experiments, it is preferable that theheight difference H1 is about 0.2 mm or less although it depends on apitch of the set tooth, a shape, a size and kinds of a workpiece W, andespecially when a metal is cut, a suitable value of the heightdifference H1 is 0.1 mm or less.

[0089] In the saw blade 1 of the first embodiment, since the saw teethhaving small set amounts and the saw teeth having large set amounts havesubstantially the same tooth heights, although saw teeth having smallset amounts function less than the saw teeth having large set amounts,the former saw teeth always carry out the cutting operation in thecutting direction. Whereas, according to the saw blade 3 of the secondembodiment, when a solid material is cut, the saw teeth Ln, Rn and St ofthe second teeth group B do not carry out the cutting operation in thecutting direction almost at all, and most of the cutting operation iscarried out by the saw teeth of the first teeth group A. Therefore, ifattention is paid only to the saw teeth of the first teeth group A whichcarry out the cutting operation, pitch is P1×P2, it looks as if the sawblade is the same as the conventional saw blade 101 shown in FIGS. 1Aand 1B.

[0090] Therefore, if the cutting conditions such as a running speed andcutting load of a band mill and saw blade are set to the same conditionsas those of the cutting operation by the saw blade 1 of the firstembodiment, and if a solid material is cut using the saw blade 3 of thesecond embodiment and the cutting time is compared, the result is sawblade 101≠saw blade 3<saw blade 1<saw blade 103. That is, as comparedwith the conventional saw blade 103 shown in FIGS. 2A and 2B and the sawblade 1 of the first embodiment shown in FIGS. 6A, 6B and 6C, thecutting time of the solid material by the second embodiment is improved,and is almost the same as the cutting time of the conventional saw blade101 shown in FIGS. 1A and 1B.

[0091] On the other hand, if a workpiece W such as a pipe material shownin FIG. 5 is cut using a saw blade 3 shown in FIGS. 7A, 7B and 7C, whenthe pitch P1 of the saw blade is as small as 2 mm with respect to the 3mm thickness of the pipe material and the cutting resistance in thecutting direction is small and the cutting amount tends to be increased,i.e., when the saw blade 3 reaches near the center of the pipe material,the saw teeth of the second teeth group B also carry out the cuttingoperation, the workpiece W does not enter between the tips of the sawblade 3, abrupt free fall is not generated and thus, the cuttingoperation is carried out appropriately without breaking the teeth.

[0092] In the sawblade 3, it is possible to equally set set amounts ofthe saw teeth of the first teeth group A and the saw teeth of the secondteeth group B as shown in FIG. 7C. In this case, the cutting precisionof a cutting section is enhanced by the shaving effect.

[0093]FIGS. 8A and 8B show a saw blade 5 of a third embodiment of theinvention. The saw blade 5 is equal to the saw blade 3 of the secondembodiment shown in FIGS. 7A, 7B and 7C from which the spur tooth Settooth of the second teeth group B is removed, and the pitches P1 betweenthe saw teeth are equal to each other.

[0094] More specifically, the first teeth group A comprises total threeteeth, i.e., one spur tooth S having high tooth height, and a pair ofleft and right set teeth Lw and Rw having relatively large set amounts.The second teeth group B comprises total two teeth, i.e., a pair of leftand right set teeth Ln and Rn having tooth height lower than the leftand right set teeth Lw and Rw of the first teeth group A and having setamount smaller than the set teeth Lw and Rw of the first teeth group A.The total five saw teeth of the combination of the saw teeth of thefirst teeth group A and the saw teeth of the second teeth group Bconstitute one set pattern.

[0095] Since the height difference H1 between the tips of the saw teethof the first teeth group A and the saw teeth of the second teeth group Bis the same as that of the saw blade 3 of the second embodiment,explanation thereof is omitted.

[0096] According to the saw blade 5 of the third embodiment, like thesaw blade 3 of the second embodiment, if a solid material is cut, theset teeth Ln and Rn of the second teeth group B do not carry out thecutting operation almost at all, and the saw teeth belonging to thefirst teeth group A carry out the cutting operation. If attention ispaid only to the saw teeth of the first teeth group A which carry outthe cutting operation, although the average pitch of the saw teeth ofthe set pattern in the saw blade 3 of the second embodiment is 4 mm, theaverage pitch of the saw teeth of the set pattern of the saw blade 5 ofthe third embodiment is slightly small as about 3.3 mm [=(2+4+4)/3].

[0097] Therefore, if the cutting conditions such as a running speed andcutting load of a band mill and saw blade are set to the same conditionsas those of the cutting operation by the saw blades of the first andsecond embodiments, and if a solid material is cut using the saw blade 5of the third embodiment and the cutting time is compared, the result issaw blade 101≠saw blade 3<saw blade 5<saw blade 1<saw blade 103. Thatis, although the cutting time of the solid material is increased ascompared with the saw blade 3 by a value obtained by subtracting about3.3 mm average pitch of the first teeth group A from the 4 mm pitch ofthe conventional saw blade 101 shown in FIGS. 1A and 1B, the cuttingtime is enhanced as compared with the conventional saw blade 103 shownin FIGS. 2A and 2B and the saw blade 1 of the first embodiment shown inFIGS. 6A, 6B and 6C.

[0098] When a workpiece W such as a pipe material shown in FIG. 5 forexample is cut using a saw blade 5 shown in FIGS. 8A and 8B, the sameeffect as that of the saw blade 3 of the second embodiment is exhibited,and the cutting operation is carried out appropriately without breakingthe teeth.

[0099]FIGS. 9A and 9B show a saw blade 7 according to a fourthembodiment of the invention. In this saw blade 7, the set amounts of theleft and right set teeth Lw and Rw of the first teeth group A and theset amounts of the left and right set teeth Ln and Rn of the secondteeth group B of the third embodiment shown in FIGS. 8A and 8B aresubstantially the same, and the pitches P1 between the saw teeth areequal to each other.

[0100] More specifically, the first teeth group A comprises total threeteeth, i.e., one spur tooth S having high tooth height, and a pair ofleft and right set teeth Lw and Rw having relatively large set amountsand high tooth heights. The second teeth group B comprises total twoteeth, i.e., a pair of left and right set teeth Ln and Rn having toothheight lower than the left and right set teeth Lw and Rw of the firstteeth group A and having set amounts which are substantially equal tothose of the set teeth Lw and Rw of the first teeth group A. The totalfive saw teeth of the combination of the saw teeth of the first teethgroup A and the saw teeth of the second teeth group B constitute one setpattern.

[0101] According to the saw blade 7 of the above structure, when thecutting resistance is large and the cutting speed is relatively smalllike a case in which a solid material shown in FIG. 3 is cut, the setteeth Ln and Rn having low tooth height of the second teeth group B donot carry out the cutting operation almost at all but slightly carry outthe cutting operation such as to scrub a side surface of a groove whichis cut by the set teeth Lw and Rw having tooth height of the first teethgroup A, and the precise of the cut surface is enhanced by the shavingeffect. Since the height difference H1 between the tips of the saw teethof the first teeth group A and the saw teeth of the second teeth group Bis the same as that of the saw blade 3 of the second embodiment,explanation thereof is omitted.

[0102] In the saw blade 7 of the fourth embodiment, if attention is paidonly to the saw teeth of the first teeth group A which mainly carry outthe cutting operation when a solid material is cut, like the saw blade 5of the third embodiment, the average pitch of the saw teeth of the setpattern is about 3.3 mm. Therefore, if the cutting conditions such as arunning speed and cutting load of a band mill and saw blade are set tothe same conditions as those of the cutting operation by the saw bladesof the first, second and third embodiments, and if the cutting time whena solid material is compared, the result is saw blade 101≠saw blade3<saw blade 5≠saw blade 7<saw blade 1<saw blade 103.

[0103] That is, although the cutting time of the solid material isincreased as compared with the conventional saw blade 103 shown in FIGS.2A and 2B and with the saw blade 1 of the first embodiment, and thecutting time is substantially the same as that of the saw blade 5 of thethird embodiment shown in FIGS. 8A and 8B.

[0104] When a workpiece W such as a pipe material shown in FIG. 5 forexample is cut using a saw blade 7 shown in FIGS. 9A and 9B, the sameeffect as that of the saw blade 3 of the second embodiment is exhibited,and the cutting operation is carried out appropriately without breakingthe teeth.

[0105] Referring to FIGS. 10A and 10B, in a saw blade 9 according to afifth embodiment of the present invention, the order of arrangement ofthe left and right set teeth Lw and Rw of the first teeth group A andthe left and right set teeth Ln and Rn of the second teeth group B ofthe saw blade 5 of he third embodiment shown in FIG. 3 are changed, andpitches P1 between the saw teeth are equal to each other. Since the sawblade 7 is almost the same as the saw blade 5 of the third embodimentshown in FIGS. 8A and 8B in function, detailed explanation is omitted.

[0106] In the saw blade 9 of the fifth embodiment, the arrangement ofthe left and right set teeth Lw and Rw of the first teeth group A andthe left and right set teeth Ln and Rn of the second teeth group B canappropriately be changed. In this case, the left and right set teeth Lwand Rw of the first teeth group A and the left and right set teeth Lnand Rn of the second teeth group B are arranged such that the saw teethin the same direction are not continuously arranged.

[0107] Referring to FIGS. 11A and 11B, in a saw blade 11 of a sixthembodiment of the invention, left and right set teeth Ln₂ and Rn₂ havinglow tooth height and small set amount are added to the second teethgroup B of the saw blade 5 of the third embodiment shown in FIG. 3, andthe number of saw teeth is increased, and the pitches 1 between the sawteeth are equal to each other.

[0108] More specifically, the first teeth group A comprises total threeteeth, i.e., one spur tooth S having high tooth height, and a pair ofleft and right set teeth Lw and Rw having relatively large set amountsand high tooth heights. The second teeth group B comprises total fourteeth, i.e., a pair of left and right set teeth Ln₁ and Ln₂ having toothheight lower than the left and right set teeth Lw and Rw of the firstteeth group A and having set amounts which are substantially equal tothose of the set teeth Lw and Rw of the first teeth group A and a pairof left and right set teeth Rn₁ and Rn₂. The total seven saw teeth ofthe combination of the saw teeth of the first teeth group A and the sawteeth of the second teeth group B constitute one set pattern. Since theheight difference H1 between the tips of the saw teeth of the firstteeth group A and the saw teeth of the second teeth group B is the sameas that of the saw blade 3 of the second embodiment, detailedexplanation thereof is omitted.

[0109] According to the saw blade 11 of the sixth embodiment, like thesaw blade 5 of the third embodiment, when a solid material is cut, thesaw teeth Ln₁, Ln₂, Rn₁, Rn₂ of the second teeth group B do not carryout the cutting operation almost at all, and the set teeth S, Lw and Rwof the first teeth group A mostly carries out the cutting operation.Therefore, if attention is paid only to the left and right set teeth Lwand Rw of the first teeth group A, the distance between the left andright set teeth Lw and Rw and a distance between the set tooth Rw andthe spur tooth S are large (P1×3=6 mm), the cutting amount of the sawteeth is increased and a load of each tooth is increased correspondinglyby a value of the increased pitch. Therefore, this is not preferable fora saw blade having relatively large pitch but this structure pattern iseffective for a saw blade having a small pitch.

[0110] When a workpiece W such as a pipe material shown in FIG. 5 is cutusing the saw blade 11 shown in FIGS. 11A and 11B, the same effect asthat of the saw blade 3 of the second embodiment is exhibited, and thecutting operation is carried out appropriately without breaking theteeth.

[0111] Referring to FIGS. 12A and 12B, in a saw blade 13 of a seventhembodiment of the invention, left and right set teeth Lw₂ and Rw₂ havinghigh tooth height and relatively large set amount are added to the firstteeth group A of the saw blade 5 of the third embodiment shown in FIGS.8A and 8B, and the number of saw teeth is increased, and the pitches 1between the saw teeth are equal to each other.

[0112] More specifically, the first teeth group A comprises total fiveteeth, i.e., one spur tooth S having high tooth height, and two pairs ofleft and right set teeth Lw₁, Lw₂, Rw₁, Rw₂ having relatively large setamounts and high tooth heights. The second teeth group B comprises totaltwo teeth, i.e., a pair of left and right set teeth Ln and Rn havinglower tooth height and smaller set amounts than the left and right setteeth Lw and Rw of the first teeth group A. The total seven saw teeth ofthe combination of the saw teeth of the first teeth group A and the sawteeth of the second teeth group B constitute one set pattern.

[0113] According to the saw blade 13 of the seventh embodiment, adrawback caused by the fact that the pitches of the left and right setteeth Lw and Rw of the first teeth group A of the saw blade 11 of theembodiment shown in FIGS. 11A and 11B is solved. Since the cuttingeffect with respect to a solid material and a pipe material, and theheight difference H1 between the tips of the saw teeth of the firstteeth group A and the saw teeth of the second teeth group B are the sameas that of the saw blade 5 of the third embodiment, detailed explanationthereof is omitted. As described above, the kinds and the number of thesaw teeth of the first teeth group A and the second teeth group B canappropriately be changed.

[0114] Referring to FIGS. 13A and 13B, according to a saw blade 15 of aneighth embodiment of the invention, a set pattern of a combination ofthe left and right set teeth Lw and Rw of the first teeth group A andthe left and right set teeth Ln and Rn of the second teeth group B, andpattern of height difference of the tooth height of the third embodimentshown in FIGS. 8A and 8B are the same as those of the saw blade 15, andthere are two kinds of pitches between the saw teeth, i.e., the pitchesare not equal to each other.

[0115] Since the pitch is not equal, there is a new effect that noise atthe time of cutting operation can be reduced. FIG. 13A shows two kindsof pitches P1 and p2, but if the kinds of the pitches are increased, itis possible to effectively restrain the resonance caused by vibration atthe time of cutting operation, and the cutting noise can further bereduced.

[0116] Since the cutting effect with respect to a solid material and apipe material, and the height difference H1 between the tips of the sawteeth of the first teeth group A and the saw teeth of the second teethgroup B are the same as that of the saw blade 5 of the third embodiment,detailed explanation thereof is omitted.

[0117] Referring to FIGS. 14A and 14B, according to a saw blade 17 of aninth embodiment of the present invention, a set pattern is constitutedby total six saw teeth of a combination of a first teeth group A havingthree teeth, i.e., a spur tooth Saw blade 1 and the left and right setteeth Lw and Rw, and the second teeth group B having three teeth, i.e.,a spur tooth S2 and the left and right set teeth Ln and Rn.

[0118] The tooth heights of the spur tooth S2 and the left and right setteeth Ln and Rn belonging to the second teeth group B are lower than thetooth heights of the spur tooth S1 and the set teeth Lw and Rw belongingto the first teeth group A, and the front garret is shallower than thefront garret of the set tooth belonging to the first teeth group A as inthe previous embodiments. The height difference H1 between the firstteeth group A and the second teeth group B are the same as heightdifference of each saw blade. The set amounts of the left and right setteeth Ln and Rn belonging to the second teeth group B are smaller thanor equal to the set amounts of the left and right set teeth Lw and Rwbelonging to the first teeth group A. The teeth S1, Lw, Rw belonging tothe first teeth group A and the saw teeth S2, Ln, Rn belonging to thesecond teeth group B are alternately arranged.

[0119] In the saw blade 17, the tip pitch P1 including garrets of thesaw teeth S2, Ln, Rn belonging to the second teeth group B is smallerthan the tip pitch P2 including garrets of the teeth S1, Lw, Rwbelonging to the first teeth group A. The left and right set teeth Lwand Rw belonging to the first teeth group A and the left and right setteeth Ln and Rn belonging to the second teeth group B may becontinuously arranged such that saw teeth which are bent in the samedirection and adjacent to each other such as to pair up with each otheras shown in FIG. 14B, or may be continuously arranged such that suchthat saw teeth which are bent in the different directions and adjacentto each other such as to pair up with each other as shown in FIG. 14C.

[0120] According to the saw blade 17 of the above structure, when asolid material W as shown in FIG. 3 is cut, the saw teeth S1, Lw, Rwbelonging to the first teeth group A mainly contribute to the cuttingoperation, and when a pipe material is cut, both the saw teeth S1, Lw,Rw belonging to the first teeth group A and saw teeth S2, Ln, Rnbelonging to the second teeth group B contribute to the cuttingoperation, and it is possible to easily cut a solid material or pipematerial.

[0121] In a saw blade 19 according to a tenth embodiment of the presentinvention shown in FIGS. 15A and 15B, arrangement of the saw blade 19,the set pattern and saw teeth is the same as the saw blade 15 the setpattern and saw teeth of the eighth embodiment, but a relief angle ofthe tip is formed in two stages to increase the garret capacity so thatclogging caused by swarf is not generated easily. Further, since thecutting effect of the saw teeth belonging to the second teeth group B issmaller than the saw teeth belonging to the first teeth group A, a depthof the front garret of the saw teeth belonging to the the first teethgroup A is set shallower than the front garret of the saw teethbelonging to the first teeth group A, so that the structure is suitablefor functions of the saw teeth.

[0122] The left and right set teeth Lw and Rw belonging to the firstteeth group A and the left and right set teeth Ln and Rn belonging tothe second teeth group B may be continuously arranged such that sawteeth which are bent in the same direction and adjacent to each othersuch as to pair up with each other as shown in FIG. 15B, or may becontinuously arranged such that such that saw teeth which are bent inthe different directions and adjacent to each other such as to pair upwith each other as shown in FIG. 15C.

[0123] As will be understood by explanations of the saw blades 17 and19, kinds and the number of saw teeth belonging to the first teeth groupA are not limited, and kinds and the number of saw teeth belonging tothe first teeth group B are not limited. When a set pattern isconstituted by combining the saw teeth of the first teeth group A andthe saw teeth of the second teeth group B, it is preferable that thenumber of left set teeth and the number of right set teeth included inthe set pattern are equal to each other. In the set pattern, the tippitches are not limited to the two kinds, i.e., P1 and P2, and anotherpitches may be combined. For example, in the set pattern, all pitchesmay be different.

1. A saw blade in which a set pattern comprising a combination of afirst teeth group having a spur tooth and left and right laterally bentset teeth and a second teeth group having left and right laterally bentset teeth is appropriately repeated, wherein set amounts of the left andright set teeth of the second teeth group are smaller than or equal toset amounts of the left and right set teeth of the first teeth group. 2.A saw blade according to claim 1, wherein the second teeth groupincludes a spur tooth, the number of teeth of the first teeth group andthe number of teeth of the second teeth group are the same.
 3. A sawblade according to claim 2, wherein the number of the left and right setteeth of the first teeth group and the number of left and right setteeth of the second teeth group are the same.
 4. A saw blade accordingto claim 3, wherein the first teeth groups and the second teeth groupsare alternately arranged.
 5. A saw blade according to claim 4, whereinthe number of teeth of the second teeth group is greater than the numberof teeth of the first teeth group.
 6. A saw blade according to claim 4,wherein the number of teeth of the first teeth group is greater than thenumber of teeth of the second teeth group.
 7. A saw blade according toclaim 6, wherein set teeth of the left and right set teeth of the firstand second teeth group which are bent in the same direction arecontinuously arranged.
 8. A saw blade according to claim 7, wherein setteeth of the left and right set teeth of the first and second teethgroup which are bent in the same direction are not continuouslyarranged.
 9. A saw blade according to claim 8, wherein pitches betweenthe teeth are not equal to each other.
 10. A saw blade according toclaim 9, wherein the non equal pitches are two kinds of pitches.
 11. Asaw blade according to claim 10, wherein a height difference between theteeth of the first teeth group and the teeth of the second teeth groupis 0.2 mm or less.
 12. A saw blade according to claim 11, wherein abottom of a garret of the saw tooth of the second teeth group is locatedcloser to a tip than a garret of the saw tooth of the first teeth group.13. A saw blade in which a set pattern comprising a combination of afirst teeth group having a spur tooth and left and right laterally bentset teeth and a second teeth group having left and right laterally bentset teeth is appropriately repeated, wherein a tooth height of thesecond teeth group is lower than a tooth height of the first teethgroup.
 14. A saw blade according to claim 13, wherein set amounts of theleft and right set teeth of the second teeth group are smaller than orequal to set amounts of the left and right set teeth of the first teethgroup.
 15. A saw blade according to claim 13, wherein the second teethgroup includes a spur tooth, the number of teeth of the first teethgroup and the number of teeth of the second teeth group are the same.16. A saw blade according to claim 15, wherein the number of the leftand right set teeth of the first teeth group and the number of left andright set teeth of the second teeth group are the same.
 17. A saw bladeaccording to claim 16, wherein the first teeth groups and the secondteeth groups are alternately arranged.
 18. A saw blade according toclaim 17, wherein the number of teeth of the second teeth group isgreater than the number of teeth of the first teeth group.
 19. A sawblade according to claim 18, wherein the number of teeth of the firstteeth group is greater than the number of teeth of the second teethgroup.
 20. A saw blade according to claim 19, wherein set teeth of theleft and right set teeth of the first and second teeth group which arebent in the same direction are continuously arranged.
 21. A saw bladeaccording to claim 20, wherein set teeth of the left and right set teethof the first and second teeth group which are bent in the same directionare not continuously arranged.
 22. A saw blade according to claim 21,wherein pitches between the teeth are not equal to each other.
 23. A sawblade according to claim 22, wherein the non equal pitches are two kindsof pitches.
 24. A saw blade according to claim 23, wherein a heightdifference between the teeth of the first teeth group and the teeth ofthe second teeth group is 0.2 mm or less.
 25. A saw blade according toclaim 24, wherein a bottom of a garret of the saw tooth of the secondteeth group is located closer to a tip than a garret of the saw tooth ofthe first teeth group.
 26. A saw blade in which a set pattern comprisinga combination of first and second teeth group each having at least aspur tooth and a pair of left and right laterally bent set teeth isappropriately repeated, wherein a tooth height of the saw tooth of thesecond teeth group is lower than a tooth height of the saw tooth of thefirst teeth group, a tip pitch including a garret of the saw tooth ofthe second teeth group is smaller than a tip pitch including a garret ofthe saw tooth of the first teeth group, set amounts of the left andright set teeth of the second teeth group are equal to or smaller thanset amounts the left and right set teeth of the first teeth group.
 27. Asaw blade according to claim 26, wherein the saw tooth of the secondteeth group is disposed between set teeth of the first teeth group. 28.A saw blade according to claim 27, wherein the second teeth groupincludes a spur tooth, the number of teeth of the first teeth group andthe number of teeth of the second teeth group are the same.
 29. A sawblade according to claim 28, wherein the number of the left and rightset teeth of the first teeth group and the number of left and right setteeth of the second teeth group are the same.
 30. A saw blade accordingto claim 29, wherein the first teeth groups and the second teeth groupsare alternately arranged.
 31. A saw blade according to claim 30, whereinthe number of teeth of the second teeth group is greater than the numberof teeth of the first teeth group.
 32. A saw blade according to claim31, wherein the number of teeth of the first teeth group is greater thanthe number of teeth of the second teeth group.
 33. A saw blade accordingto claim 32, wherein set teeth of the left and right set teeth of thefirst and second teeth group which are bent in the same direction arecontinuously arranged.
 34. A saw blade according to claim 33, whereinset teeth of the left and right set teeth of the first and second teethgroup which are bent in the same direction are not continuouslyarranged.
 35. A saw blade according to claim 34, wherein pitches betweenthe teeth are not equal to each other.
 36. A saw blade according toclaim 35, wherein the non equal pitches are two kinds of pitches.
 37. Asaw blade according to claim 36, wherein a height difference between theteeth of the first teeth group and the teeth of the second teeth groupis 0.2 mm or less.
 38. A saw blade according to claim 37, wherein abottom of a garret of the saw tooth of the second teeth group is locatedcloser to a tip than a garret of the saw tooth of the first teeth group.39. A saw blade in which a set pattern comprising a combination of afirst teeth group having at least a spur tooth and a pair of left andright laterally bent set teeth and a second teeth group having at leasta pair of left and right set teeth is appropriately repeated, wherein atooth height of the saw tooth of the second teeth group is lower than atooth height of the saw tooth of the first teeth group, a tip pitchincluding a garret of the saw tooth of the second teeth group is smallerthan a tip pitch including a garret of the saw tooth of the first teethgroup, set amounts of the left and right set teeth of the second teethgroup are equal to or smaller than set amounts the left and right setteeth of the first teeth group.
 40. A saw blade according to claim 39,wherein the saw tooth of the second teeth group is disposed between setteeth of the first teeth group.
 41. A saw blade according to claim 40,wherein the second teeth group includes a spur tooth, the number ofteeth of the first teeth group and the number of teeth of the secondteeth group are the same.
 42. A saw blade according to claim 41, whereinthe number of the left and right set teeth of the first teeth group andthe number of left and right set teeth of the second teeth group are thesame.
 43. A saw blade according to claim 42, wherein the first teethgroups and the second teeth groups are alternately arranged.
 44. A sawblade according to claim 43, wherein the number of teeth of the secondteeth group is greater than the number of teeth of the first teethgroup.
 45. A saw blade according to claim 44, wherein the number ofteeth of the first teeth group is greater than the number of teeth ofthe second teeth group.
 46. A saw blade according to claim 45, whereinset teeth of the left and right set teeth of the first and second teethgroup which are bent in the same direction are continuously arranged.47. A saw blade according to claim 46, wherein set teeth of the left andright set teeth of the first and second teeth group which are bent inthe same direction are not continuously arranged.
 48. A saw bladeaccording to claim 47, wherein pitches between the teeth are not equalto each other.
 49. A saw blade according to claim 48, wherein the nonequal pitches are two kinds of pitches.
 50. A saw blade according toclaim 49, wherein a height difference between the teeth of the firstteeth group and the teeth of the second teeth group is 0.2 mm or less.51. A saw blade according to claim 50, wherein a bottom of a garret ofthe saw tooth of the second teeth group is located closer to a tip thana garret of the saw tooth of the first teeth group.